Stability analysis of emulsified pectin based matrix for phage microencapsulation

DINI C; ISLAN GA; CASTRO GR

Taipei, Taiwan

Conferencia; 5th International Conference on Industrial Bioprocesses; 2012

National Taiwan University of Science and Technology - National Taiwan University - National Cheng Kung University - National Chung Hsing University

In a previous work, phage against entherohemorragic E. coli was encapsulated on microspheres withlow methoxylated pectin (33% D.E.) emulsified with oleic acid (10% v/v) for oral delivey. This matrixin vitro is able to protect phage from the simulated acid gastric conditions and easily released phage insimulated intestinal environment. The phage release kinetics showed a marked dependence ontemperature, being faster as the temperature increased. The aim of this work is to analyze the correlationof the release profiles with theoretical models and evaluate the effect of temperature, pH and lipaseactivity on matrix stability.Matematical modelling of experimental data obtained for phage release kinetics at 19, 30 and 37°C bestfitted the Korsmeyer-Peppas model in where the fraction of encapsulated agent released is dependent ontn. In this model difussion as well as relaxation of the matrix are taken into account and the value of timeexponent (n)characterizes the phage release mechanism. The phage release kinetics model equationsobtained showed n values above 0.85 at the three temperatures assayed indicating a super case IItransport mechanism.Analysis of the matrix swelling in PBS (pH 7.2) at 30 and 37°C showed a maximum weight incrementafter 4h incubation: 74,0% and 78,7% respectively. Thenceforth, a decrease in microspheres weightwas observed, due to matrix degradation. Matrix swelling kinetic was slower at 19ºC. Matrixdegradation occurs by bulk erotion since no reduction in the microspheres diameter was observed after4h of incubation. This is in agreement with the results obtained by texturometric assays of swollenmicrospheres. The analysis of a 30% deformation of the microspheres showed a significant descrease inmicrospheres hardness and consistency (p < 0.05) after the first 60 min. incubation at 30 and 37°C ,showing reduction percentajes in the range of 61.5 ? 79.6% and 68.9 ? 80.2% respectively. The effect oflipase addition and acidity on matrix stability was also analyzed. Presence of lipase (1 mg ml-1) reducedgel swelling in 4.5% with respect to PBS after 30 min incubation (p< 0.05). The microspheres incubatedat pH 1.2 showed a reduction of 12.7% in weight after 30 min.Equilibrium gel swelling analysis performed by incubation of the microspheres for 24h at 25°C inMES-Tris-gly buffer (2 mM) at pH values from to 9 showed no difference in beads? weight.The results obtained show that the release kinetics at different temperatures correlates with theKorsmeyer-Peppas model with n values indicating a super case II transport mechanism in agreementwith the high swelling power and the reduction of matrix integrity observed by texturometric assays.Lipases, present in the intestine, slightly reduced matrix swelling power with respect to the PBS alone.This assays predict a release of most of phage cargo within few hours when the microspheres reach theintestinal fluids. This type of burst release of phage is suitable for phage therapy since phage is aself-replicating therapeutic agent not affected by proteases present in the intestinal environment thusonce phage is released it could go over the intestinal tract without inactivating.